Method and apparatus for producing a foamed meat or fish product

ABSTRACT

The invention relates to a method of producing a foamed meat product, comprising the steps of: feeding a pumpable raw material containing comminuted meat or fish and strand-like connective tissue components to a dispersing apparatus with a chamber with a cylindrical rotor arranged therein, which is provided, on its circumference, with a number of cavities to create cavitation, feeding a gas to the dispersing apparatus and operating the dispersing apparatus while creating cavitation and dispersing the gas supplied, in the process of which the sinews or ligaments are passed through the chamber, and creating a foamed meat or fish product containing strand-like connective tissue components, which can be sterilised.

The invention relates to a method and an apparatus for producing afoamed meat or fish product and to a foamed meat or fish product.

Compared to conventional, compact meat products, a foamed meat productoffers a number of advantages, especially in the field of pet food. Thelight, smooth structure already gives the food a pleasant appearance.The increased volume and the reduced density of a foamed meat productalso result in a reduction in the calorie density and the specificcalorie content within a particular volume, as a result of which it iseasier to maintain or reduce a given body weight. In addition, itresults in a changed taste experience while eating, improved digestionand also, in the case of certain species, such as cats or dogs, whichtend to a suboptimal liquid intake, it creates the possibility ofimproving the intake of liquid, together with the solid food.

Especially in the production of pet food products, the problem existsthat it is on the one hand desirable also to use less expensive parts,such as animal by-products, as the raw material, while, on the otherhand, some parts, such as in particular sinews, ligaments, twisted orcoiled sheaths round connective tissue (epimysium, perimysium and/orendomysium) or similar strand-like, fibrous or filamentouscollagen-containing parts of connective tissue, are very difficult tocomminute and resist the comminution procedures conventionally used,which then leads to clogging and other difficulties in apparatuses ofthe kind conventionally used for foaming meat mixtures.

Meat and animal by-products contain not only the desirable muscleproteins (myofibrillary protein) and meat proteins (sarcoplasmaticprotein), but also connective, structural and supporting tissue (stromaproteins). The most important connective tissue is collagen, togetherwith elastin and reticulin, proteins from cell membranes and otherproteins. The connective and supporting tissues comprise sinews,ligaments, fascia, skin and hide and are found in arteries, veins andseparating tissues such as basal membranes (basal lamina) and also takethe form of fibres and membranes which form a sheath round eachindividual muscle fibre (endomysium), bundles of muscle fibres(perimysium) and entire muscles (epimysium), fat cells or organs inanimal tissue.

Because of the great strength and elasticity of this connectivetissue—compared to the muscle tissue—, the connective tissue membranesround, in particular, sinews and ligaments (the latter mainly containcollagen of types I, III, IV, XII, XIX) are not chopped small enoughduring the comminution of meat or animal by-products, e.g. by cutters ormincers. Collagens, which can account for up to ⅓ of the entire bodyprotein, are structural proteins of the skin, connective tissue andbones. As structural proteins, they determine the structure of the celland thus ultimately the nature of the tissue and of the entire physique.After the meat and animal by-products have been comminuted in order toproduce a fine meat mixture or meat emulsions, washing processes toextract the muscle tissue can reveal that these meat products containlong twisted connective tissue membranes, sinews and ligaments—which areas yet not heat-treated.

Even after the products have been comminuted by passing them through a 2mm perforated disk or when they are emulsified through a 0.3 mm wideblade gap, it is still possible to find sinews, membranes and ligamentsin the meat mixture with a total length of more than 40 mm.

During the production of meat emulsions, the muscle proteins arepartially released from their matrix by the addition of salts,phosphates and other minerals. The connective tissue fibres and sinewsetc. remain present in the meat mixture as coiled membranes and fibres.When this meat mixture is conveyed by positive-displacement pumps pastmeasuring probes, mixer fingers, conventional static mixers or flowdividers installed transversely to the direction of flow, it is foundthat these fittings gradually become clogged by the longer fibroussinews, twisted membranes and/or connective tissue fibres. If thesefibrous parts from the meat mixture continue to collect on the fittings,it is even possible for entire pipes to become blocked.

The presence of sinews, ligaments or twisted and connective tissuemembranes of this kind in meat emulsions produced on an industrial scaleis probably also the reason why right down to the present day, noindustrially homogeneously foamed meat products have become establishedon the market. This is the reason why in the patent literature (e.g. JP2219562 A, U.S. Pat. No. 6,475,551 B2) on the foaming of meat products,either only silent cutters, bowl choppers or pressurised gassing areused, because these processes are not excessively disturbed by sinews,ligaments and membranes. The foam structure obtained with theseprocesses is inhomogeneous, however, and is not stable. It is notpossible to produce fine, stable foams from highly viscous liquid foamsin this way.

The processes mentioned therefore only use meat with the sinews removed,or pure muscle tissue (lean meat). Formulations consisting of high-pricematerials of this kind and containing no sinews or long connectivetissue fibres are then foamed using conventional rotor/stator systems(e.g. Hansa-Mixer, Mondo-Mix). The conventional foaming systems aretherefore not suitable for foaming formulations containing fibres, sincethe fibres are deposited on and collect around the pins (fingers) of therotors and around the pins (fingers) of the stators of the mixers, whichthen jam.

It is known from EP 1 289 638 B1 to disperse liquids with gases bydeliberately causing cavitation.

The invention therefore set out to provide a method and an apparatus forproducing a foamed meat product with which it is readily possible alsoto process raw materials containing the above-mentioned strand-likeconnective tissue components, such as sinews and similar strip-like orfibrous parts (e.g. ligaments, fibres, fascia, skins, hides).

From the point of view of the procedure, this problem is solved inaccordance with the invention by a method of producing a foamed meatproduct, comprising the steps of: feeding a pumpable raw materialcontaining comminuted meat and strand-like components of connectivetissue, such as partially uncomminuted sinews and/or ligaments and/orconnective tissue membranes, to a dispersing apparatus with a chamberwith a cylindrical rotor positioned therein, which is provided, on itscircumference, with a number of cavities to create cavitation, feeding agas to the dispersing apparatus, operating the dispersing apparatuswhile creating cavitation and dispersing the gas fed in, in the processof which the sinews are passed through the chamber in particular withoutcomminution, and creating a foamed meat product containing strand-likecomponents of connective tissue, such as partially uncomminuted sinewsand/or ligaments and/or connective tissue membranes.

So that meat containing foams remain stable for an adequate storagetime, i.e. retaining their texture, the viscosity of the liquid phasemust be as high as possible and the gas bubbles as small as possible.Separation processes resulting from the differences in density can bedelayed in this way. For long-term stability, the liquid phase of thefoam must be converted into a solid phase. In the present invention,this is achieved by a heating step or sterilisation, in which theprotein of the meat, fish and slaughterhouse by-products are denaturedand gelled. The conventional rotor/stator foaming processes are alsoonly suitable to a limited extent for foaming highly viscous media,since high pumping pressures are required in order to overcome the smallgaps resulting from the necessary high speeds with the maximum number ofpins on the rotor and stator. Excessive heating of the product, combinedwith thermal damage to the protein, then leads to a reducedsolidification of the protein in the foam during sterilisation andresults in a less stable foam. Similarly, it is not possible to achievestable foams with low densities of 0.4 to 0.6 g/ml with these processes.

A mixing and foaming apparatus known as the “Hansa-Mischer” uses rotorand stator members covered with pins, where rotor pins have a square 6×6mm cross-section, for example 15 mm upstream and downstream of a pin ineach case is the distance from the stator pins, for example. Lowdensities require high speeds with the maximum number of pins possible.With a wider pin spacing and low speeds, parts can be passed through,but in this way, with sufficiently high viscosities (necessary in orderto stabilise the foam), it is not possible to obtain stable foams withsmall gas bubble sizes. The use, in accordance with the invention, ofthe cavitation rotor makes it possible to foam highly viscous fibrousformulations and to achieve small, homogeneously distributed gasbubbles.

The viscosities of the meat emulsions in accordance with the inventionand the foams obtained are at least 5,000, 10,000, 15,000, 20,000,25,000, 30,000, 35,000, 40,000, 45,000 or 50,000 cP at 20° C., and, byway of example, 10,000-40,000 cP, preferably 15,000 to 35,000 cP,especially 16,000 to 34,000 cP, most especially 20,000 cP to 34,000 cP.Measurements can be made with a Brookefield R+S rheometer with spindle 6at 20 r.p.m. at a foam temperature of 20° C. and density of approx. 0.5g/ml.

The strand-like components mentioned, such as sinews and/or ligamentsand/or connective tissue membranes may have a minimum length in the rawmaterial or in the foamed meat product of 3 mm, 5 mm, 10 mm, 15 mm, 20mm, 25 mm or 30 mm, and they may be present in a proportion of at least0.5% by weight, 1% by weight, 2% by weight, 5% by weight, 10% by weightor 20% by weight in the non-sterilised state, or in a proportion of atleast 0.1% by weight, 0.2% by weight, 0.5% by weight, 1% by weight, 2%by weight or 5% by weight in the sterilised state, based in each case onthe dry substance.

It may be provided that additives such as water, fat, oil, salt,emulsifiers, spices, gels, vegetable components, leaves or fibres,vegetables, cereals, starch, hydrocolloids, proteins, minerals,colorants and preservatives in comminuted or uncomminuted form aremetered into the raw material, especially before its entry into thedispersing apparatus.

It is expedient, after starting or restarting the dispersing apparatus,for an amount of meat product corresponding to about one to 1.5 timesthe free content of the chamber of the dispersing apparatus to bereturned to the starting material.

It is advantageous for the starting material to be lowered to atemperature of less than 30° C., preferably less than 25° C., 20° C.,17° C., 15° C., 12° C. or between 2° and 8° C., especially to 5° C.before it enters the dispersing apparatus.

It may be provided that the dispersing apparatus is operated in such away that a density of the meat or fish product produced of 0.3 to 0.95g/ml, preferably from 0.4 to 0.7 g/ml and particularly preferably from0.45 to 0.6 g/ml is set.

It may be provided that the meat or fish product produced is fed to ametering apparatus and filled in containers after it exits thedispersing apparatus. One proposal in this context is that after themeat product produced exits the dispersing apparatus, i.e. while it isbeing fed from the dispersing apparatus to a metering apparatus, it isconveyed continuously at an overpressure and is thus exposed to anoverpressure, which may lie in a range from 0.5 to 6.0 bar, preferablyfrom 1.0 to 5.0 bar and more preferably from 2.0 to 4.0 bar.

The invention preferably provides that after it exits the dispersingapparatus, a first partial flow of the meat or fish product produced ismixed with an additive, such as a colorant, and is passed through astatic mixing apparatus. After it exits the static mixing apparatus, thepartial flow may be fed, together with a second flow of the meat or fishproduct produced, to a mixing head, so that partial strands of a streamof material produced with different compositions, such as differentcolours, can be formed.

It may be provided that as the gas, helium, hydrogen, nitrogen, air,oxygen, argon, NH₃, N₂O, CO₂ or any mixture of one or more of thosegases is used.

It is preferably proposed that if there should be any interruption ofthe filling process, the meat product produced is circulated for apredetermined time from the output of the dispersing apparatus, througha cooling apparatus, to the inlet of the dispersing apparatus. In theprocess, it is in particular proposed that the meat product is cooled.

The foamed meat or fish product is preferably sterilised at atemperature between 110° C. and 130° C. for a period of between 10 and50 minutes. In the sterilised product, an average gas bubble size of 0.1to 7 mm, preferably from 0.15 to 5 mm, more preferably from 0.2 mm to 3mm and even more preferably from 0.3 to 2 mm, such as 0.5 to 0.9 mm, ispreferably produced.

It is appropriate for the density of the meat product produced to bedetermined continuously and for the amount of the gas to be supplied tobe determined on this basis.

In terms of the apparatus, the problem underlying the invention issolved by an apparatus for producing a foamed meat or fish product,comprising a dispersing apparatus with a chamber with a cylindricalrotor positioned therein, which is provided on its circumference with anumber of cavities to create cavitation, with a feeding pump coupled toan inlet of the dispersing apparatus, a gas delivery apparatus beingdisposed between the feeding pump and the inlet, and with a return lineextending from an outlet of the dispersing apparatus to the inlet andwith a cooling apparatus disposed in the course of the return line.

It may be provided that during operation of the metering apparatus, abuffer container is filled with foamed meat or fish product, themetering apparatus is no longer operated after a predetermined fillinglevel of the buffer container is reached, foamed meat or fish product isremoved from the buffer container to fill containers, and after apredetermined emptying level of the buffer container is reached, themetering apparatus is operated again, and the buffer container is againfilled until the predetermined filling level is reached.

It may be provided that a metering apparatus for filling meteredportions of the foamed meat products into containers is connected to theoutlet of the dispersing apparatus.

A density measuring apparatus and/or a pressure measuring apparatusand/or a temperature measuring apparatus may be positioned downstream ofthe outlet from the dispersing apparatus, preferably between the outletfrom the dispersing apparatus and a branch point at which the returnline branches off.

A density measuring apparatus and/or a pressure measuring apparatusand/or a temperature measuring apparatus may be positioned upstream ofthe dispersing apparatus, preferably between the feeding pump and theinlet of the dispersing apparatus.

Between the outlet from the dispersing apparatus and the meteringapparatus, two partial flow paths may be formed, a first partial flowpath being connected to a first inlet of a mixing head, and a secondpartial flow path containing a feeder for additives, such as colorants,and a static mixing apparatus, and being connected to a second inlet ofthe mixing head.

The static mixing apparatus may possess a central canal or passage andmixing fingers pointing diagonally downwards into it.

The invention also relates to a foamed meat or fish product containingcomminuted meat or fish and strand-like connective tissue componentssuch as, in particular, sinews and/or ligaments and/or connective tissuemembranes, it being possible for the strand-like connective tissuecomponents to be partially uncomminuted. In the sterilised state (heatedto 110° C. to 130° C. for 10 to 50 minutes), the meat product preferablycontains an average gas bubble size of 0.1 to 7 mm, more preferably from0.2 mm to 3 mm and even more preferably from 0.3 to 2 mm, and especially0.4 to 0.9 mm. In this context, it is preferably envisaged that the meatproduct contains a weight ratio, based on dry matter, of strand-likeconnective tissue components with a length of more than 0.3 mm of 0.10%to 20% by weight, especially 0.11% to 10%, 0.12% to 5% or 0.13% to 3%,which can be determined by washing out over a 0.3 mm mesh sieve.

It may be provided that the meat product contains uncomminuted pieces ofmeat with a size of 3 to 20 mm.

In addition, the meat product may contain additives such as water, fat,oil, salt, emulsifiers, spices, gels, vegetable components, leaves orfibres, vegetables, cereals, starch, hydrocolloids, proteins, minerals,colorants and preservatives in comminuted or uncomminuted form.

The invention will now be explained by describing worked embodiments,reference being made to a drawing, in which

FIG. 1 shows a worked embodiment of an apparatus in accordance with theinvention.

FIG. 2 shows a section view of a first variant of a dispersingapparatus,

FIG. 3 a shows a section view of a second variant of a dispersingapparatus,

FIG. 3 b shows a schematic view of the second variant of the dispersingapparatus,

FIG. 3 c shows a view of the dispersing apparatus according to FIG. 3 bin cross-section,

FIG. 3 d shows a perspective view of a rotor of the dispersing apparatusaccording to FIG. 3 b,

FIG. 4 shows details of the supply of gas to the dispersing apparatus,

FIGS. 5 a-d show a static mixing element in a number of views,

FIG. 6 shows a cumulative frequency distribution of the gas bubble sizesin the foamed, sterilised meat product, and

FIG. 7 shows a detailed gas bubble size distribution.

The method and apparatus of the invention will be explained below withreference to the exemplary illustration of an apparatus for producing ameat product in accordance with FIG. 1 which contains gas bubbles or isfoamed.

Meat (and/or fish) to be processed in accordance with the invention isfed in a cooled or frozen state to a comminution apparatus 2, in whichit is chopped to a size that makes it possible to process the foamedproduct. Comminution to a size of less than 3 mm, preferably less than 1mm, less than 0.5 mm or less than 0.1 mm is appropriate. In the process,meat fibres and any bones present can be comminuted to the dimensionsstated. Since, however, sinews, ligaments, twisted connective tissuemembranes and similar elements are very difficult to comminute, becauseof their structure and strength, they may remain with little comminutionor uncomminuted in the otherwise comminuted meat.

It may be provided in this context that, in addition to the amount ofstrand-like connective tissue components, such as sinews and/orligaments, which is present in any case in the meat or fish to beprocessed, an additional amount may be added as well, which may come,for example, from the processing of meat into products in which acontent of connective tissue components such as sinews or ligaments isundesirable and from which the latter are removed.

A sample formulation for the production of a foamed meat product willnow be explained. A portion of meat and animal by-products (especiallypoultry liver, poultry gizzards, poultry separator meat, pigs' stomachs,pigs' lungs) amounts to approx. 45 to 55% by weight, especially 52% byweight. Water is added in a proportion of approx. 30 to 40% by weight,especially 36% by weight. Emulsifiers and salts are also added.

A first pump 4 conveys the comminuted meat to a mixer 6, in whichadditives are metered in as required and depending on the formulationand mixed with the meat. Examples of such additives are water, fat, oil,salt, ice, emulsifiers, spices, gels, vegetable components, leaves,fibres, vegetables, cereals, starch, hydrocolloids, proteins, minerals,colorants and preservatives in comminuted or uncomminuted form.

A second pump 12 conveys the meat preparation further to a finecomminution apparatus 14, which forms an emulsifying station at the sametime.

After the mixture exits the emulsifier 14 and, where applicable, afurther pump 12, a gas with which the meat preparation is to be foamedis supplied at a gas inlet 16. In principle, any gas suitable for usewith foodstuffs may be used for this purpose, such as helium, hydrogen,nitrogen, oxygen, argon, NH₃, N₂O, CO₂, air etc., though those gases areparticularly suitable which are both inert, i.e. oxygen-free inparticular, and which exhibit the lowest possible solubility in water,or in the meat preparation to be foamed. Nitrogen exhibits considerablylower solubility than CO₂ and is therefore preferable as a matter ofprinciple.

A gas-supply unit, here for example a pressure-swing adsorption unit 18(FIG. 4), supplies pressurised nitrogen via an air filter, a pressurereducing valve 20, a flow meter 22, a needle valve 24, a cut-off valve26 and a check valve 28 to the gas inlet 16, where the gas enters thecomminuted and emulsified meat preparation in metered form.

The gas/meat mixture is delivered to a dispersing apparatus 30 in theform of a shock wave reactor, in which the gas is dispersed into smallgas bubbles. The structure and action of the dispersing apparatus 30 areexplained by FIGS. 2 and 3.

FIG. 2 shows a first embodiment of the dispersing apparatus 30 (shockwave reactor) and FIG. 3 a second embodiment in various views, whichconsists substantially of a cylindrical chamber 32 closed on all sides,in which a rotor 34 is mounted such as to be rotatable about an axis ofrotation 36. The rotor 34 is likewise cylindrical and is spaced apart onall sides from the peripheral and end walls of the chamber 32, so thatthe space formed in this way (free chamber volume) is filled with thegas/meat mixture to be processed.

Arranged on the periphery of the rotor 34 are a number of radiallyaligned bore holes 40, which lead in a manner known per se to theformation of shock waves and cavitation bubbles, which collapse and leadin this way to a fine dispersion of the gas supplied. The dispersionprocess is indicated in FIG. 2 in that the gas supplied is present inrelatively large bubbles 42, whereas the product exiting contains finelydispersed gas bubbles, which are merely hinted at in FIG. 2.

The cavitation bubbles formed collapse principally in the interior ofthe bore holes 40 and lead to extremely great shear forces and pressurewaves, which result not only in a particularly fine dispersion of thegas supplied, but also in a relatively uniform size distribution, or ina limited scatter in the size distribution of the gas bubbles formed.

When the dispersing apparatus 30 is started or restarted, the desiredproduct quality is not obtained immediately, but experience has rathershown that about 1 to 2 times, preferably 1.5 times the free chambervolume must be passed through the dispersing apparatus before a steadyoperating state is reached. In order to avoid having to reject as wastethe material produced during such a starting-up period which does notmeet the requirements, a return line 44 and optionally a further pump 12is provided, with which the material can be circulated via thedispersing apparatus 30. A cooling apparatus 46 ensures that the heatintroduced into the product by the dispersing apparatus 30 isdissipated, because the gas bubble content means that heating of theproduct is undesirable, and also that emulsified fats remain largelysolid. A temperature of less than 30° C., preferably less than 25° C.,20° C., 17° C., 15° C., 12° C. or between 2° C. and 8° C., andespecially 5° C. is appropriate. During the recirculation of theproduct, neither gas nor meat preparation is supplied.

Material exiting the dispersing apparatus 30 can be recirculated notonly in the course of a startup process, but also, if the need arises,in the event of a delay in the filling area, so that the dispersingapparatus does not need to be switched off in such cases. In particular,it is appropriate to cool the recirculated material with the coolingapparatus 46 in such a case.

In addition, it is possible to arrange a buffer container in anyconvenient location downstream of the dispersing apparatus 30, such asafter the mixing head 82 or immediately before the filler head 94, whichmakes it possible to receive a certain amount of the foamed meat or fishproduct, such as 10, 20, 50 or 100 times a amount envisaged for fillinga container, so that a corresponding number of containers can be filledfrom the buffer container. Since the throughput of the dispersingapparatus cannot as a rule be adjusted exactly to the flow of materialwhich is filled through the filler head 94 averaged out over time, it ispossible to have the dispersing apparatus 30 running in cycles until thebuffer container is filled, then to switch it off and only to switch itback on when the buffer container has been emptied to a set residuallevel, such as 5% or 10% of its capacity.

Two branches 52, 53 are arranged downstream of an outlet 50 from thedispersing apparatus 30, the first branch 52 leading to the coolingapparatus 46, and a first partial flow path 54 and a second partial flowpath 56 following on from the second branch 53. The first partial flowpath 54 can be closed with a cut-off valve.

First of all, an inlet 60 for additives is provided in the secondpartial flow path 56, to which a colorant metering pump 62 is connectedin the example illustrated. Alternatively, any other additive could beintroduced at this point, e.g. vegetables or cereal paste, gels, aspic,gravy, dairy products, hydrocolloids, starch, proteins, minerals,colorants and preservatives, and/or a meat or fish emulsion or asuspension containing pieces of meat or fish can be dispersed in.

After the inlet 60 comes a static mixing unit 64, in which a series ofstatic mixing members 66 are arranged. FIG. 7 shows a static mixingmember 66 in different views, the mixing member consisting substantiallyof a length of cylindrical pipe with mixing surfaces 68 arrangedradially and axially and pointing inwards, and with a mixing finger 70arranged between them.

When the throughput is sufficient, a good mixing effect results, so thatthe additive previously introduced is mixed with the foamed meatproduct. When the throughput is low, a dispersing effect is caused.Because of the arrangement of the inclined mixing surfaces pointingdown-stream and the mixing fingers, fibre-like components of the foamedmeat product and especially the sinews, ligaments etc. contained in it,can move through the mixing members with no difficulty and do not becometrapped. Preferably, a number of mixing members 66 are arranged inseries, especially aligned at 90° to one another, as is made clear bypositioning projections 72 and corresponding positioning recesses 74arranged at 90° thereto, which are disposed on the respective axial endsof a mixing member and with which two adjacent mixing members can becoupled in a positive fit.

The first partial flow path 54 is connected to a first inlet 80 of amixing head 82, while the second partial flow path 56 is connected to asecond inlet 84 of the mixing head 82.

In operation, it can be provided that that 50% to 95%, such as 85%, ofthe material exiting the dispersing apparatus 30 flows through the firstpartial flow path 54, while the remaining amount flows through thesecond partial flow path 56 and the static mixing unit 64.

A filler head 94 serving as a metering apparatus follows the mixing head82. In this context, it is proposed that the material exiting thedispersing apparatus 30 is introduced into the filler head 94 via aback-pressure valve 95 and a static mixing unit 64. The arrangement of aback-pressure valve has the advantage that upstream, i.e. in thedispersing apparatus 30, a particular minimum pressure can bemaintained, e.g. at least 1.5 bar or a pressure between 2 and 2.5 bar.At least one pressure sensor 98 and a density measuring device 97 areprovided in order to ensure that as far as the filler head 94 anoverpressure of approx. 0.5 to 6 bar, preferably 1 to 4 bar and morepreferably 1.5 to 3 bar prevails within the material conveyed. Thereason why this is important is that, because of the gas content, thefoamed material must as far as possible not be exposed to a partialvacuum in certain cases, in order not to impair the gas bubblestructure.

Alternatively, a conventional filling apparatus can be installeddownstream of the mixing head, with an intake and dispensing station, atwhich material coming from the mixing head is optionally drawn in inmetered amounts and dispensed in metered amounts.

Beneath the filler head there are scales, with which the filling of aparticular container 102 is monitored and the filling procedure isterminated. Downstream of the filler head, there is a metering apparatus106 for lumpy additives. After that, closing, sealing and sterilisationdevices are positioned.

After part of the available filling volume of the container 102, e.g.70% to 90% of it, has been filled with the foamed meat product, the restof the available filling volume, or part of it, can be filled with lumpyadditives such as vegetables, fruit, cereals, pieces of meat,slaughterhouse by-products, meat analogues, pieces of fish, fishanalogues, surimi, pieces of egg, pieces of fruit, nuts or pieces ofnut.

The invention is suitable for implementing various product concepts,such as a) meat or fish foam with nothing added, b) meat foam withvegetables and/or cereals added, c) meat foam with vegetable or cerealpastes introduced in a marbled pattern, the density of which is approx.1 g/ml, d) meat foam with pieces of meat mixed in, slaughterhouseby-products and/or meat analogues (chunks), e) meat foam with pieces ofmeat and/or meat analogues in layers at the top or bottom, f) meat foamwith a layer of gel/aspic at the top or bottom, which may also containpieces of meat, meat analogues, pieces of vegetable or cereals, g) meatfoam with pieces of meat, pieces of vegetable or meat analogues inlayers at the top or bottom, which are present in a gravy, h) meat foamcontaining pieces of egg mixed in or in layers at the top or bottom,possibly in gravy or in gel/aspic, i) meat foam containing individualfoods mixed in or in layers at the top or bottom, possibly in gravy orin gel/aspic (individual foods: meat or animal by-products, milk anddairy products, eggs and egg products, oils and fats, yeasts, fish andfish by-products, cereals, vegetables, vegetable by-products, vegetableprotein extracts, minerals, sugar, fruits, nuts, seeds, algae, molluscsand crustaceans, insects, bakery products).

One method of detecting connective tissue in fresh meat has been furtherdeveloped on the basis of Strange and Whiting (Strange E. D., Whiting,R. C., “Effects of added connective tissues on the sensory andmechanical properties of restructured beef steaks”, Meat Science 27,(1990) pp. 61-74) for detecting connective tissue even in heat-treated,foamed fish/meat products:

Materials:

-   -   1. Stainless-steel analytical sieve (0.300 mm), Retsch    -   2. 2,000 g 15% H₃PO₄ solution (20° C., pH 1; 1.5 M H₃PO₄)    -   3. 1,000 g 5% NaOH solution (20° C., pH 12.2; 1.25 M NaOH)    -   4. Aqua dest. (20° C.) for rinsing solid samples on the        analytical sieve    -   5. Mixer “3MIX 7,000”, Krups, mixing member: egg-beater    -   6. Colloid mill MK/MKO, IKA magic LAB, IKA GmbH & Co. KG,        speed=12,000 r.p.m., 450° setting angle (1¼ turns on the setting        ring: radial gap=0.398 mm    -   7. Laboratory analytical balance, Sartorius    -   8. Drying cabinet T 6030, Heraeus Thermo Scientific    -   9. Desiccator

Method:

-   -   1. Determine the dry mass (DM in %) of the sample (at 104° C.        until constant weight is reached)    -   2. Comminute/stir approx. 50-55 g sample (weigh in precisely P)        with 100 ml water for 30 s with a hand mixer on level 1 with        egg-beaters.    -   3. Comminute the suspension through the IKA colloid mill: —IKA        MK/MKO (radial gap 0.398 mm=>1¼ turns); rinse the colloid mill        with water.    -   4. Separate solids via a stainless-steel sieve with a mesh width        of 0.30 mm.    -   5. Leave solids/residue for 5 hours in 500 ml NaOH solution        (stir occasionally)    -   6. Separate solids again with a stainless-steel sieve with a        mesh width of 0.30 mm. Rinse off caustic soda remaining on the        sieve with water    -   7. Steep the sieve with the residue in the phosphoric acid for        60 seconds    -   8. Rinse the sieve with water    -   9. Dry the sieve at 104° C. until constant weight is reached    -   10. Weigh the dry mass retained (R) on the 0.30 mm sieve    -   11. Express the results:        -   proportion of fibrous connective tissue [>0.30 mm;            %]=((R)×100)/((DM in %)×(P))

Amounts of connective tissue found in this way in foamed products beforeand after sterilisation:

TABLE 1 Dried fibrous and solid connective tissue determined by washingout over 0.3 mm sieve (shown in % by Recovery rate of weight of the drymass of the foamed fibrous and solid meat/fish product investigated)connective tissue, before sterilisation after sterilisation after 95%95% sterilisation [%] Foamed confidence Aver- confidence aftersterilisation meat/fish Average interval age interval Average product[%] +/− [%] [%] +/− [%] [%] with trout 10.56 2.65 1.13 0.29 10.71 withsalmon 6.75 0.42 0.89 0.36 13.20 with beef 6.70 0.83 1.18 0.27 17.67with chicken 7.19 1.15 0.73 0.14 10.13

After sterilisation, lower figures are regularly found for the remainingstrand-like connective tissue components, because the majority of thecollagen from the membranes etc. is degraded to water-soluble gelatineduring the sterilisation process. Sinews are detected very well with themethod.

TABLE 2 Dried fibrous and solid connective tissue determined by washingout over 0.3 mm sieve Recovery rate (shown in % by weight of the dry offibrous and mass of the raw material used) solid connective beforesterilisation after sterilisation tissue, after 95% 95% sterilisation[%] confidence confidence after sterilisation Average interval Averageinterval Average [%] +/− [%] [%] +/− [%] [%] Chicken liver 0.137 0.0540.017 0.012 12.42 Pig's lung 8.504 0.604 1.177 0.651 13.84 Debonedturkey meat 2.516 0.247 0.100 0.025 3.96 Pig's stomachs 7.081 2.8220.678 0.349 9.57 Cattle lung 12.075 1.918 2.492 1.148 20.64 Chickengizzards 7.321 1.761 0.913 0.341 12.47 Trout cut-offs 3.626 0.328 0.3810.136 10.51 Salmon cut-offs 4.740 0.344 0.388 0.117 8.19 Duck meat 0.9530.160 0.090 0.013 9.42

Table 2 shows the amounts and recovery rates of strand-like connectivetissue components for different types of meat.

The high proportion of larger connective tissue (larger than 0.30 mm)before foaming makes it clear how necessary it is to use a method thatcan process high viscosities irrespective of the fibres or pieces andwhich ensures a fine gas distribution.

FIGS. 6 and 7 show a cumulative frequency distribution and a detailedgas bubble size distribution.

The diameters of the gas bubbles of equal volume d _(3.2) in thesterilised foam range from approx. 20-2,000 μm diameter. The mean wasapprox. 0.73 mm diameter.

The Reynolds numbers when mixing or dispersing other pumpable componentsinto the foam were found to lie in the range 0.0010<Re<0.0150.

Pumpable component (vegetable paste): 0.0023<Re<0.0051.Average Re number at the mixing point: 0.0140<Re<0.3,000.

The fluctuations are due to the formation of the average speeds: In onecase, the average was formed over the mass, and in the secondcalculation it was formed over the flow surfaces.

Formulation Information: EXAMPLE 1 Foamed Meat/Fish Product (Batch Size80 kg)

Vitamin/mineral/nutrition mix:  1.80 % Emulsifiers (individually or a 1.00% combination of substances in accordance with the list ofemulsifiers for animal feed from “Community Register of Feed Additivespursuant to Regulation (EC) No 1831/ 2003, Appendices 3 & 4, Annex: Listof additives (status: Released 21 May 2010.)” Vegetable fibre powder 3.00% (SBP, cellulose) Hydrocolloid 0.20% (e.g. CMC carboxy-methyl-cellulose or individual or a combination of substances from the list ofadditives for animal feed from “Community Register of Feed Additivespursuant to Regulation (EC) No 1831/2003, Appendices 3 & 4, Annex: Listof additives (status: Released 21 May 2010.)” Pigs' blood plasma powder 2.00% Turkey separator meat  5.00% Chicken gizzards  6.00% Pig'sstomachs 12.00% Chicken liver 14.00% Pigs' lungs 15.00% Water 40.00%

Process Information:

All the meat is frozen (−18° C.) and comminuted to approx. 20×20 mm.

In a Paddle Mixer:

1st step: mix meat with minerals for 3 minutes.2nd step: add half the water (30° C.) and mix for a further 2 minutes.3rd step: add remaining dry ingredients, rotate for 1 minute in eachdirection.4th step: add emulsifier and remaining water.

Before emptying, mix for approx. one minute to drain. Total mixing timeapprox. 10 min.

The meat mixture is now at a temperature of approx. +2° C. and isemulsified in an emulsifying apparatus through a combination of bladesand 1.5 mm perforated disks. The mixture is now at a temperature ofapprox. 5° C.

The mixture is then conveyed at a mass flow of 2.2 kg/min, with theaddition of 2.2 l nitrogen or comressed air through a shock wave reactor(ex HydroDynamics, Rome, Ga., US). The speed of the rotor is 1,800r.p.m. The rotor has a diameter of 304.8 mm and a width of 50.75 mm. 2parallel rows of holes, each with 30 holes, are arranged on thecircumference. The individual holes have a diameter of 18.8 mm and adepth of 50 mm. The volume of a hole is 13.5 ml. The distance betweenthe circumference of the rotor and the fixed housing is ¼″=6.4 mm.

The temperature of the foam obtained in this way is: 32.0° C. At thistemperature, the foam can be filled directly, controlled by gravimetry,volumetry or pressure.

After the foam has been filled in a suitable container (tin, bowl,pouch), and the latter has been sealed and sterilised thermally (T>110°C.), a stable product is obtained (fully preserved), which can be storedat room temperature for at least 2 years. The stable foam product ischaracterised by a homogeneous distribution of the gas bubbles, a moist,shiny, solid foam texture and a high level of acceptance by pets.

EXAMPLE 2 Foamed Meat Product with Fish (Batch Size 80 kg)

Vitamin/mineral/nutrition mix: 2.00 % Emulsifiers (individually or acombination of 1.00% substances in accordance with the list ofemulsifiers for animal feed from “Community Register of Feed Additivespursuant to Regulation (EC) No 1831/2003, Appendices 3 & 4, Annex: Listof additives (status: Released 21 May 2010.)” Vegetable fibre powder(SBP, cellulose) 1.30% Hydrocolloid 0.20% (as in Example 1) Pigs' bloodplasma powder 1.50% Turkey separator meat 5.00% Chicken gizzards 6.00%Pig's stomachs 12.00% Chicken liver 13.00% Pigs' lungs 13.00% Salmonby-products 7.00% Water 38.00%

Process Information:

All the meat and fish materials are frozen (−18° C.) and comminuted toapprox. 20×20 mm.

In a Paddle Mixer:

1st step: mix meat with minerals for 3 minutes.2nd step: add half the water (30° C.) and mix for a further 2 minutes.3rd step: add remaining dry ingredients, rotate for 1 minute in eachdirection.4th step: add emulsifier and remaining water.

Before emptying, mix for approx. one minute to drain. Total mixing timeapprox. 10 min.

The mixture of meat and fish is now at a temperature of approx. +2° C.and is emulsified in an emulsifying apparatus through a combination ofblades and 1.5 mm perforated disks. The mixture is now at a temperatureof approx. 5° C.

The mixture is then conveyed at a mass flow of 2.0 kg/min, with theaddition of 2.0 l nitrogen or comressed air through a shock wave reactor(ex HydroDynamics, Rome, Ga., US). The speed of the rotor is 2,200r.p.m. The rotor has a diameter of 266 mm and a width of 50.75 mm. 2parallel rows of holes, each with 24 holes, are arranged on thecircumference. The individual holes have a diameter of 18.8 mm and adepth of 50 mm. The volume of a hole is 13.5 ml. The distance betweenthe circumference of the rotor and the fixed housing is ¼″=6.4 mm.

The temperature of the foam obtained in this way is 31.0° C. At thistemperature, the foam can be filled directly, controlled by gravimetry,volumetry or pressure.

After the foam has been filled in a suitable container (tin, bowl,pouch), and the latter has been sealed and sterilised thermally (T>110°C.), a stable product is obtained (fully preserved), which can be storedat room temperature for at least 2 years. The stable foam product ischaracterised by a homogeneous distribution of the gas bubbles, a moist,shiny, stable foam texture and a high level of acceptance by pets.

EXAMPLE 3 Foamed Meat Product with Fish (Batch Size 80 kg)

Vitamin/mineral/nutrition mix: 2.70 % Emulsifiers (individually or a1.00% combination of substances in accordance with the list ofemulsifiers for animal feed from “Community Register of Feed Additivespursuant to Regulation (EC) No 1831/2003, Appendices 3 & 4, Annex: Listof additives (status: Released 21 May 2010.)” Vegetable fibre powder(SBP, cellulose) 3.00% Hydrocolloid 0.30% (as in Example 1) Pigs' bloodplasma powder 2.00% Turkey separator meat 4.00% Chicken gizzards 6.00%Pig's stomachs 11.00% Chicken liver 13.00% Pigs' lungs 12.00% Troutby-products 6.00% Water 39.00%

Process Information:

All the meat and fish materials are frozen (−18° C.) and comminuted toapprox. 20×20 mm.

In a Paddle Mixer:

1st step: mix meat with minerals for 3 minutes.2nd step: add half the water (30° C.) and mix for a further 2 minutes.3rd step: add remaining dry ingredients, rotate for 1 minute in eachdirection.4th step: add emulsifier and remaining water.

Before emptying, mix for approx. one minute to drain. Total mixing timeapprox. 10 min.

The mixture of meat and fish is now at a temperature of approx. +2° C.and is emulsified in an emulsifying apparatus through a combination ofblades and 1.5 mm perforated disks. The mixture is now at a temperatureof approx. 5° C.

The mixture is then conveyed at a mass flow of 2.0 kg/min, with theaddition of 2.0 l nitrogen or comressed air through a shock wave reactor(ex HydroDynamics, Rome, Ga., US). The speed of the rotor is 1,500r.p.m. The rotor has a diameter of 203 mm and a width of 50.75 mm. 2parallel rows of holes, each with 18 holes, are arranged on thecircumference. The individual holes have a diameter of 18.8 mm and adepth of 50 mm. The volume of a hole is 13.5 ml. The distance betweenthe circumference of the rotor and the fixed housing is 1″=25.4 mm.

The temperature of the foam obtained in this way is 21.0° C. At thistemperature, the foam can be filled directly, controlled by gravimetry,volumetry or pressure.

After the foam has been filled in a suitable container (tin, bowl,pouch), and the latter has been sealed and sterilised thermally (T>110°C.), a stable product is obtained (fully preserved), which can be storedat room temperature for at least 2 years. The stable foam product ischaracterised by a homogeneous distribution of the gas bubbles, a moist,shiny, stable foam texture and a high level of acceptance by pets.

It is possible to use the following permitted additives:

Emulsifiers for Animal Feed from: “Community Register of Feed AdditivesPursuant to Regulation (EC) No 1831/2003, Appendices 3 & 4, Annex: Listof Additives (Status: Released 21 May 2010.)”

EC No. Additives: Emulsifiers E 322 Lecithins E 432 Polyoxyethylene(20)sorbitan monolaurate E 433 Polyoxyethylene(20) sorbitan mono-oleate E434 Polyoxyethylene(20) sorbitan monopalmitate E 435 Polyoxyethylene(20)sorbitan monostearate E 436 Polyoxyethylene(20) sorbitan tristearate E471 Mono and diglycerides of edible fatty acids E 472 Mono anddiglycerides of edible fatty acids esterified with: a) acetic acid b)lactic acid c) citric acid d) tartaric acid e) monoacetyl and diacetyltartaric acid E 473 Sugar esters (esters of saccharose and edible fattyacids) E 474 Sugar glycerides (mixture of saccharose esters and mono anddiglycerides of edible fatty acids) E 475 Polyglycerine esters of ediblefatty acids E 477 Monoesters of proylene glycol (1.2-propane diol) andof edible fatty acids, alone or mixed with diesters E 480Stearyl-2-lactylic acid E 481 Sodium stearyl lactyl-2-lactate E 482Calcium stearyl lactyl-2-lactate E 483 Stearyl tartrate E 484Polyethylene glycol glyceryl ricinoleate E 487 Polyethylene glycolsoybean oil fatty acid ester E 488 Polyethylene glycol glyceryl tallowfatty acid ester E 489 Polyglycerine ether with the alcohols obtained byreduction of oleic acid and palmitic acid E 491 Sorbitan monostearate E492 Sorbitan tristearate E 493 Sorbitan monolaurate E 494 Sorbitanmono-oleate E 495 Sorbitan monopalmitate E 496 Polyethylene glycol 6,000E 497 Polymers of polyoxypropylene-polyoxyethylene (M.G. 6,800-9,000) E498 Partial polyglycerine esters of polycondensed ricinoleic fatty acidsThickening and Gelling Agents for Animal Feed from: “Community Registerof Feed Additives Pursuant to Regulation (EC) No 1831/2003, Appendices 3& 4, Annex: List of Additives (Status: Released 21 May 2010.)”

EC No. Additives: E 400 Alginic acid E 401 Sodium alginate E 402Potassium alginate E 403 Ammonium alginate E 404 Calcium alginate E 405Propylene glycol alginate (1.2-propane diol alginate) E 406 Agar-agar E407 Carrageenan E 410 Carob seed flour E 411 Tamarind seed flour E 412Guar seed flour, guar gum E 413 Gum tragacanth E 414 Gum arabic E 415Xanthan gum E 418 Gellan gum E 440 Pectins E 460 Microcrystallinecellulose E 460(ii) Cellulose powder E 461 Methyl cellulose E 462 Ethylcellulose E 463 Hydroxypropyl cellulose E 464 Hydroxypropyl methylcellulose E 465 Methyl ethyl cellulose E 466 Carboxymethyl cellulose(sodium salt of the cellulose carboxymethyl ether) E 470 Sodium,potassium or calcium salts of the edible fatty acids, alone or mixed,obtained either from edible fats or from distilled edible fatty acids E486 Dextrans E 498 Partial polyglycerine esters of polycondensedricinoleic fatty acids E 499 Cassia gum

LIST OF REFERENCE NUMERALS

-   2 Comminution apparatus-   4 First pump-   6 Mixer-   8 Second pump-   12 Third pump-   16 Gas inlet-   18 Pressure-swing adsorption unit-   20 Pressure controller-   22 Flow meter-   24 Needle valve-   26 Cut-off valve-   28 Check valve-   30 Dispersing apparatus-   32 Chamber-   34 Rotor-   36 Axis of rotation-   40 Bore hole-   42 Gas bubble-   44 Return line-   46 Cooling apparatus-   50 Outlet-   52 Branch-   54 First partial flow path-   56 Second partial flow path-   60 Inlet-   62 Colorant metering pump-   64 Static mixing unit-   66 Static mixing member-   68 Mixing surface-   70 Mixing fingers-   72 Positioning projection-   74 Positioning recess-   80 First inlet-   82 Mixing head-   84 Second inlet-   94 Filler head-   95 Back-pressure valve-   97 Density measuring device-   98 Pressure sensor-   102 Container-   106 Metering apparatus

1. Method for producing a foamed meat or fish product, comprising:feeding a pumpable raw material, containing comminuted meat or fish andstrand-like components of connective tissue to a dispersing apparatushaving a chamber and a cylindrical rotor positioned therein, which has anumber of cavities arranged on its circumference for creatingcavitation, feeding a gas to the dispersing apparatus, operating thedispersing apparatus while creating cavitations and dispersing the gasfed in, the strand-like components of connective tissue being fedthrough the chamber, and creating a foamed meet or fish productcontaining strand like components of connective tissue.
 2. The method asclaimed in claim 1, characterized in that additives such as water, fat,oil, salt, emulsifiers, spices, gels, vegetable components, leaves orfibers vegetables, cereals, starch, hydrocolloids, proteins, minerals,colorants and preservatives in comminuted or uncomminuted form aremetered into the raw material before or after its entry into thedispersing apparatus.
 3. The method as claimed in claim 1, characterizedin that the raw material is brought to a temperature between 2° C. and8° C. before entering the dispersing apparatus.
 4. The method as claimedin claim 1, characterized in that an additive is added to a partial flowof the meat product produced after it exits the dispersing apparatus,and is passed through a static mixing unit, the partial flow, afterexiting the static mixing unit, being fed, together with another partialflow of the meat product produced, to a mixing head, whereby differentlycomposed partial strands of a flow of material produced are formed. 5.The method as claimed in claim 1, characterized in that, especially inthe event of an interruption of a filling process, the meat productproduced is circulated from the output of the dispersing apparatus via acooling apparatus to the inlet of the dispersing apparatus.
 6. Themethod as claimed in claim 1, characterized in that the meat product issterilized at a temperature of at least 110° C. for at least 10 minutes.7. The method as claimed in claim 1, characterized in that duringoperation of the metering apparatus, a buffer container is filled withfoamed meat or fish product, the metering apparatus is no longeroperated after a predetermined filling level of the buffer container isreached, foamed meat or fish product is removed from the buffercontainer to fill containers, and after a predetermined emptying levelof the buffer container is reached, the metering apparatus is operatedagain, and the buffer container is again filled until the predeterminedfilling level is reached.
 8. An apparatus for producing a foamed meat orfish product, comprising a dispersing apparatus having a chamber and acylindrical rotor positioned therein which has cavities arranged on itscircumference for creating cavitation, and a feeding pump coupled to aninlet of the dispersing apparatus, a gas delivery apparatus beingarranged between the feeding pump and the inlet, and comprising a returnline which extends between an outlet of the dispersing apparatus and theinlet, a cooling apparatus being disposed in the course of the returnline.
 9. The apparatus as claimed in claim 8, characterized in that twopartial flow paths are formed between the outlet of the dispersingdevice and a metering apparatus, a first partial flow path beingconnected to a first inlet of a mixing head, and a second partial flowpath containing a feeder for additives such as colorants and a staticmixing apparatus being connected to a second inlet of the mixing head.10. A foamed meat or fish product, comprising comminuted meat or fishand strand-like components of connective tissue, obtainable by a methodas claimed in claim
 1. 11. The foamed meat or fish product as claimed inclaim 10, characterized in that the meat or fish product is sterilizedand has an average gas bubble size from 0.1 to 7 mm.
 12. The foamed meator fish product as claimed in claim 11, characterized in that the meator fish product contains a weight ratio of strand-like connective tissuewith a length of 0.3 mm of 0.1% by weight to 20% by weight.